1. Field
The present invention relates generally to wireless power, and more specifically, to systems, device, and methods related to an interface for monitoring a battery temperature in both wired and wireless charging applications.
2. Background
Approaches are being developed that use over the air power transmission between a transmitter and the device to be charged. These generally fall into two categories. One is based on the coupling of plane wave radiation (also called far-field radiation) between a transmit antenna and receive antenna on the device to be charged which collects the radiated power and rectifies it for charging the battery. Antennas are generally of resonant length in order to improve the coupling efficiency. This approach suffers from the fact that the power coupling falls off quickly with distance between the antennas. So charging over reasonable distances (e.g., >1-2 m) becomes difficult. Additionally, since the system radiates plane waves, unintentional radiation can interfere with other systems if not properly controlled through filtering.
Other approaches are based on inductive coupling between a transmit antenna embedded, for example, in a “charging” mat or surface and a receive antenna plus rectifying circuit embedded in the host device to be charged. This approach has the disadvantage that the spacing between transmit and receive antennas must be very close (e.g. mms). Though this approach does have the capability to simultaneously charge multiple devices in the same area, this area is typically small, hence the user must locate the devices to a specific area.
Prior to receiving a charge, a temperature of a battery within an electronic device must be monitored to ensure that the temperature is within a safe window. Typically, this is done with a thermistor, which is positioned either in a battery pack or proximate the battery pack. Co-existence of a wired charging module and wireless charging receiver within an electronic device has proven to be challenging.
A need exists for methods, systems, and devices for interfacing a single thermistor within an electronic device to a wired charging module and a wireless charging receiver while maintaining a high degree of temperature sensing accuracy.